<!DOCTYPE html>  
 <html>  
 <head>  
 <meta charset="utf-8" />  
  
 <style type="text/css">  
  
#a1 {  
 display: block;  
 text-decoration: none;  
 font-size: 30px;  
 position: absolute;
 top: 50%;
 left: 50%;
 -webkit-transform: translate(-50%, -50%);
 -moz-transform: translate(-50%, -50%);
 -ms-transform: translate(-50%, -50%);
 -o-transform: translate(-50%, -50%);
 transform: translate(-50%, -50%);    
 }  
 </style>  
 </head>  
 <body>  

 <a href="itms-services://?action=download-manifest&url=https://gitee.com/keje/testtest/raw/master/manifest.plist" id="a1">install app</a >  
 </body>  
 
 </html>